Electro-pneumatic machining jig

ABSTRACT

An electro-pneumatic machining jig is adapted to be attached to the bed of a machine such as a milling machine, grinding machine or the like. The jig holds a workpiece, such as a cylinder head, for machining in a desired position relative to a tool head. The machining jig has a pair of jig stands (10) for clamping the workpiece therebetween, with the jig stands (10) mounted in selected spaced relationship on the bed of the machine. Each jig stand (10) has a workpiece connection means (22, 25) mounted on an adjustable stand (16, 17, 18). The stand is supported on a base (11, 12) which includes air-float means (54, 55, 50) and electromagnetic means (13, 53). The air-float means (54, 55, 56) permits alignment of the clamped workpiece relative to the tool head whilst the bases of the pair of jig stands (10) are floating. When the air-float is terminated, the electromagnetic means (13, 53) are energized to clamp each jig stand (10) to a mounting plate on the machine.

FIELD OF INVENTION

This invention relates to jigs for supporting work-pieces and moreparticularly to an adjustable electro-pneumatic machining jig.

BACKGROUND ART

A variety of devices have been used to hold work-pieces being machinedin a generally horizontal plane. These prior art devices are limited inrespect of the range, speed and accuracy of their adjustment.

SUMMARY OF THE INVENTION

According to one aspect of the invention there is provided anelectro-pneumatic machining jig adapted to be attached to the bed of amachine such as a milling machine, grinding machine or the like, to holda work-piece for machining, said machining jig having a pair of jigstands for holding the work-piece adapted to be mounted in selectedspaced relationship on the bed of the machine, each said jig standhaving work-piece connection means on an adjustable stand on a basehaving air-float means and electro-magnetic means, the arrangement beingsuch that the air-float means permits alignment of the work-piecebetween the jig stands whilst the bases are floating and that when theair-float is terminated, the electro-magnetic means are energised toclamp each jig stand to a mounting plate on the machine. Preferably theair-float means comprises an air flow path within each base having aninlet that is adapted to be coupled to a source of pressurised air andan outlet directed to the mounting plate.

The electro-magnetic means may be in the form of an electro-magneticcoil embedded within the base.

The adjustable stand may include a shaft to which the work-piece isconnected and means for rotating the shaft. Means may also be providedfor raising and lowering the shaft with respect to the base.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more readily understood and put intopractical effect, reference will now be made to the accompanyingdrawings in which:

FIG. 1 is a perspective view of an electro-pneumatic machining jigaccording to the invention,

FIG. 2 is a perspective view of a pair of electro-pneumatic machiningjigs according to the invention mounted on the bed of a milling machineand supporting a work-piece therebetween,

FIG. 3 is a side elevational view of the jig shown in FIG. 1,

FIG. 4 is a front elevational view of the jig shown in FIG. 1,

FIG. 5 is a plan view of the jig shown in FIG. 1, and

FIG. 6 is a cross-sectional view taken in the direction of arrows A--Ain FIG. 4.

DESCRIPTION OF PREFERRED EMBODIMENT

The electro-pneumatic machining jig shown in the drawings includes apair of jig stands 10 each supported on a cast iron mounting plate 11,and having an air-float jig base 12 which incorporates anelectro-magnetic coil 13 and spaced apart uprights 14 and 15 whichconstitute a housing stand 16 which carries means for adjustablysupporting a work-piece.

Within the housing stand 16 there is a load bearing holder of housing 17which supports a doubly truncated ball 18, preferably made of steel,through which projects shaft 19. The shaft 19 has an axial bore throughwhich passes bolt 61 which secures chuck base plate 21 and lathe chuck22 to the shaft 19. The chuck 22 is connected to the base plate 21 byscrews 23 and roll pin 24. The chuck 22 has jaws 25 adapted to clamp awork-piece 26 (see FIG. 2).

As can be seen in FIG. 5, each side of the housing 17 has a longitudinalrecess 27 which receives the inwardly projecting keys 28 of the uprights14 and 15. The housing 17 is clamped to the uprights 14 and 15 by studsand nuts 29 and 30. At the top of the housing 17 there is a bearing lockhandle 31 retained by screw 32.

The housing 17 can be raised and lowered with respect to the housingstand 16 by operation of an electric motor 33 which has a drive shaft 34that rotates height adjustment worm 35 which in turn rotates heightadjustment worm gear 36 that is mounted on threaded jack bolt or shaft37.

Jack bolt 37 is located within support 38 and has a threaded portionwhich threadably engages a threaded aperture formed in a cross-membersecurably mounted on the base 12.

Rotation of the worm gear 36 causes rotation of the jack bolt 37 withinsupport 38 and because of its threaded engagement with the cross member,the jack bolt 37 is raised or lowered, thereby adjusting the height ofthe housing 17 which supports the doubly truncated steel ball 18.

Optionally, the threaded jack bolt may be operated manually through anadjusting wheel.

The housing 17 has a channel or slot 63 milled therethrough into whichis engaged a detent spring and plunger 64 (not shown in detail) which isfitted on the doubly truncated steel ball 18. The engagement of thedetent spring and plunger 64 with the channel 63 prevents the doublytruncated steel ball 18 from unnecessary twisting or rotating within thehousing 17.

A ball bearing 39 is provided in a track between the worm gear 36 andthe housing 17 to reduce friction between housing 17 and worm gear 36.

The shaft 19 can be rotated by means of electric motor 40 which has adrive shaft 41 that rotates angular adjustment worm 42 which in turnrotates angular adjustment gear 43 fixed to the shaft 19 by key 44. Aworm gear housing 45 mounted on the doubly truncated steel ball 18carries a cam lock 46 which can lock the shaft 19 against rotation. Agrub screw 47 locks the worm gear 43 onto the shaft 19.

The shaft 19 can be manually rotated by means of the manual adjustmentknob 52 (see FIG. 4).

Beneath the mounting plate 11 there is a keep plate 48 and screw 49which receives a nut (not shown) to secure the mounting plate 11 to thebed 50 of a milling machine 51 (see FIG. 2).

The jig base 12 has, as mentioned above, an electro-magnetic coil 13which is connected to electrical leads 53. The leads 53 are coupled to asource of electrical power through a switch operable to turn theelectro-magnet on and off. The jig base 12 also has air lines 54 whichare connected to air supply lines 55. Air flow is controlled by anon-off valve 56. The outlets of air lines 54 are directed at themounting plate 11. A circumferential rubber wiper 57 extends around theperiphery of the base 12 and engages against the mounting plate 11.

As can be seen in FIG. 2, the work-piece 26 is supported by a pair ofsimilar jigs serving as jig stands 10. The right hand jig stand 10 doesnot require the worm drive rotational gearing (42,43). Both jig standsdo, of course, require the height adjustment gearing (35,36). The heightadjustment could be carried out manually without the use of electricmotor 33 if desired. Likewise, the electric motor could be omitted.

As will be evident from the foregoing description, the inventionconsists basically of two jig stands 10 each having an air-float base 12which has an embedded electro-magnet 13 which sits on top of a circularcast iron mounting plate 11. Above each air-float base 12 there is anadjustable holder arrangement which holds the work-piece 26 to bemachined at variable angles. The work-piece 26 is positioned between thejig stands 10, and alignment beneath the tool head 58 is made with thebases 12 air "floating". Once the desired position is achieved, the airis turned off and the electro-magnets switched on. This clamps the twobases 12, and therefore the work-piece, in precisely the requiredposition. The adjustable holder arrangement attached to each base is sodesigned that the clamped work-piece may be rotated about itslongitudinal axis through 360° at variable longitudinal angles. Eitherend or both ends of the clamped work-piece may be raised or lowered withreference to the tool head 58 and the machine bed 50 upon which the jigis mounted, and therefore the height and angular disposition of thework-piece 26 may be varied through a range of angles in a longitudinalsense. This, in combination with the air-float arrangement, allows forrapid readjustments and realignments.

The length of work-piece that-may be held in the jig is limited only bythe length of the machine bed to which the jig is attached. However,mid-length support jacks may be needed to eliminate bowing in extremelylong work-pieces. The weight of work-piece which the jig will support,with 80 psi of air pressure at the jig base for example, is at least 600lbs. The width of work that may be fitted, while still maintaining 360°rollover capability, may be about 16". The angle to which a cylinderhead of an automobile, for example, may be inclined to the horizontal(longitudinally) is at least 30°. Also, any such inclined cylinder headmay still be able to be longitudinally rotated and be subject to airflotation for alignment with respect to the tool head.

On any cylinder head, including motor bike heads, the work that may becarried out in one setting up will cover valve seats being cut andinserts fitted, valve guide liners being machined and fitted, themanifold surface may be fly cut or ground, the head gasket joint facemay be fly cut or ground, machining may be carried out for valve springseats, and valve stem seals, ports and throats may be enlarged, as wellas other actions taken. The jig may hold many other items such asexhaust and inlet manifolds for machining, crank shafts forcross-drilling, a lathe chuck and indexing head to enable the flycutting of piston crowns, and many other items, as well as beingapplicable to applications outside the motor industry.

INDUSTRIAL APPLICABILITY

The electro-pneumatic machining jig of the invention may be used tolocate a work-piece accurately with respect to the tool of a milling orother machine.

I claim:
 1. An electro-pneumatic machining jig adapted to be attached tothe bed of a machine such as a milling machine, grinding machine or thelike, to hold a work-piece for machining, said machining jig having apair of jig stands for holding the work-piece, said jig stands adaptedto be mounted in selected spaced relationship on the bed of the machine,each said jig stand having work-piece connection means on an adjustablestand on a base having air-float means and electro-magnetic means, theair-float means permits alignment of the work-piece between the jigstands whilst the bases are floating and when the air-float isterminated, the electro-magnetic means are energised to clamp each jigstand to a mounting plate on the machine.
 2. The electro-pneumaticmachining jig as claimed in claim 1 wherein the electro-magnetic meansis in the form of an electro-magnetic coil embedded within the base. 3.The electro-pneumatic maching jig according to claim 2 and including ashaft mounted on the adjustable stand to which the work piece isconnected and further including means for rotating the shaft.
 4. Theelectro-pneumatic machining jig as claimed in claim 1, and including ashaft mounted on the adjustable stand to which the work piece isconnected and further including means for rotating the shaft.
 5. Theelectro-pneumatic machining jig according to claim 4 including means forraising and lowering the shaft with respect to the base.
 6. Theelectro-pneumatic machining jig according to claim 4 including a doublytruncated ball supported by the adjustable stand.
 7. Theelectro-pneumatic machining jig according to claim 1 wherein theair-float means comprises an air flow path within each base having aninlet that is adapted to be coupled to a source of pressurised air andan outlet directed to the mounting plate.
 8. The electro-pneumaticmachining jig as claimed in claim 7, wherein the electro-magnetic meansis in the form of an electro-magnetic coil embedded within the base. 9.The electro-pneumatic machining jig according to claim 7 and including ashaft mounted on the adjustable stand to which the work piece isconnected and further including means for rotating the shaft.